The present St John's Church dates back to 1908; it succeeded an earlier building which used to be situated at the corner of Crabtree Lane and Southdown Road. It was called the 'paper' church as it had been constructed on a timber framework and filled in with frail material, and was sadly, though perhaps not unexpectedly, destroyed by a spectacular fire on Sunday 31st December 1905.
Determined that the people of Southdown,(or Bowling Alley as it was then called) would not be overwhelmed by this misfortune, the Rev William Wingfield Colley, curate-in-charge on the staff at St Nicholas' church at the time became the driving force behind the building of a new church. The land for the present church on Harpenden Common was given by Sir Charles Lawes Wittewronge, son of Sir John Lawes, and was in the midst of an old orchard. One ancient tree still remains in the Vicarage garden.
It was designed by FC Eden - although a well known architect (he specialised in restoring Churches to an ornate style), he only designed two churches - the other is St George the Martyr at Wash Common, Newbury. St John's is very much the exception in his designs, being to a very simple design. The contract for the building work was given to the local Harpenden building firm Philips & Blake, and the first turf was cut by William Wingfield Colley's sister on 24th June 1907, St John the Baptist's day. As a result of this timing, St John the Baptist was adopted as the church's new patron saint.
The new church, with its wonderful sense of light, was consecrated on Monday 2nd March 1908 and celebrated its centenary in 2008.
Initially a daughter church in the parish of St Nicholas, St John's became a parish ("Harpenden St John") in its own right in 1936.